We have a requirement to have an admin screen to modify basic configuration( a file in the server/default/conf folder) for my application (lets call this myApp). We can easily create a screen to modify the file, but the myApp.war needs to be restarted to make the configuration changes get reflected immediatly. What is the best way to do that? Do we create a new admin application? If yes, how do we restart the myApp.

Which version of JBoss AS? If 6.x or earlier, there are MBeans you can call to undeploy the app, but from what I recall that ends up removing the app from the deploy directory making redeployment impossible. It sounds like the app you want to control is deployed as an exploded app; if so you could touch the web.xml file - a timestamp update will cause the app server to redeploy the app.

I don't understand the question. What part of touching the web.xml file are you having an issue with? The path should be fairly easy to get (though you might need a property to define the app's directory name), and then use the File.setLastModified() method.